Just because you have a bad experience it doesn't mean that it sucks. My experience with WPEngine has been fantastic.
What blows a story like this up (as much as hitting the front-page of HN is 'blowing up') isn't that a service failed to meet the needs of one blogger, but rather that the people running the service respond to criticism (in public) sounding more like petulant children than professionals.
As someone not into blogging, I'm not that familiar with WPEngine, but based on comments here that link to various twitter comments now I suddenly have a negative-leaning opinion of them. Primarily because they couldn't take a negative review without calling the poster a "hater". (FWIW, a lot of my negative opinion is tied up in this stupid word, which IME comes out as a last resort when the person using it knows there's a lot of truth to what the other person is saying but they refuse to acknowledge it for whatever emotional reasons).
But I wasn't asking for anything exotic. A multisite network, not very large, not much traffic. It says, right there on their site, that they support multisite networks.
So I guess I ... well ... expected that they would be able to support a multisite network.